You are the captain of a big warship, that was created to destroy enemy submarines. Enemies will attack you and the further you go - the stronger the weapons they use against you will be. Bonuses and the store will help you. when you destroy the enemy you get bonus and scores that you may spend in the store bying lives, shields, mines. You need to successfully pass 30 levels to defeat them. Be careful! Even a little mistake can destroy you.